iTunes to version 4.8
Apple released version 4.8 of iTunes a few minutes ago. The main update of the update (about 11 MB download) is the ability to directly manage the transfer of contacts and calendars from the address book and from iCal. This feature is enabled only if you use Tiger.
For other compatible operating systems (Mac OS X 10.2.8 or higher as well as Windows 2000 and XP), it is not clear what has been changed. Apple merely says that 4.8 supports "new features in the iTunes Music Store". Among the likely hypotheses are some changes to the song protection system and the security of the online sales site. At the moment it does not appear to have been placed any restriction on the use of a version of iTunes older than 4.8, as happened in the past.
To download version 4.8 you can switch from the page dedicated to iTunes. At the time of writing, the update does not seem to be available from "Software Update".